Histograms support arithmetic operations, in particular add, subtract,
multiply and divide. In all cases the operation is applied bin-by-bin, and the
histograms involved in the operation must have the same binning. The input histograms are unchanged, and a new histogram is created as the result
of the operation. All of the arithmetic operations are methods of
IHistogramFactory to reflect the fact that a new histogram is always created as a
result of the operation. For multi-dimensional histograms it is also possible to create slices and
projections.